Golf club stabilization and momentum apparatuses and methods

ABSTRACT

Golf club stabilization and momentum apparatuses and methods of use are provided herein. An example apparatus can include a body having a tubular sidewall defining a tubular channel having a sealed front end and a sealed rear end, as well as a front face. One or more objects are disposed inside the tubular channel. The objects may be weighted spheres. The one or more objects are configured to linearly translate within the tubular channel during movement of the body and impart kinetic energy to an external object in combination with the front face when the body impacts the external object. Another example apparatus can have more than one tubular sidewalls defining more than one tubular channels. Each tubular channel may have one or more objects disposed inside.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Application No. 62/199,448, filed on Jul. 31, 2015, of U.S. Provisional Application No. 62/202,868, filed on Aug. 9, 2015, of U.S. Provisional Application No. 62/205,232, filed on Aug. 14, 2015, of U.S. Provisional Application No. 62/208,768, filed on Aug. 23, 2015, and of U.S. Provisional Application No. 62/212,953, filed on Sep. 1, 2015. All of these applications are hereby incorporated by reference herein in their entireties, including all references and appendices cited therein.

FIELD

The present disclosure is generally directed to golf clubs and, more specifically, but not by limitation, to golf club heads that comprise tubular compartments that house weighted objects. A weighted object traverses linearly within a tubular compartment and functions to impart additional force to a golf ball when the golf ball is struck by the golf club head.

SUMMARY

According to some embodiments, the present disclosure is directed to an apparatus comprising: (a) a body comprising: (i) a tubular sidewall defining a tubular channel having a sealed front end and a sealed rear end; and (ii) a front face; and (b) an object disposed inside the tubular channel, the object configured to linearly translate within the tubular channel during movement of the body and impart kinetic energy to an external object in combination with the front face when the body impacts the external object.

According to some embodiments, the present disclosure is directed to an apparatus, comprising: (a) a body comprising: (i) a plurality of tubular sidewalls defining a plurality of tubular channels each having a sealed front end and a sealed rear end; and (ii) a front face; and (b) an object disposed inside each of the plurality of tubular channels, the object configured to linearly translate within the tubular channel and contact the sealed front end during an impact event to reduce rotation of the body during the impact event.

According to some embodiments, the present disclosure is directed to an apparatus, comprising: (a) a body comprising: (i) a tubular sidewall defining a tubular channel having a sealed front end and a sealed rear end; and (ii) a front face; and (b) a weighted object disposed inside the tubular channel, the weighted object imparting kinetic energy to an external object in combination with the front face when the body impacts the external object, wherein the kinetic energy imparted by the weighted object and the body in combination is greater than the kinetic energy imparted by the body without the weighted object therein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed disclosure, and explain various principles and advantages of those embodiments.

The methods and systems disclosed herein have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

FIG. 1 is a perspective view of an example apparatus, constructed in accordance with the present disclosure.

FIG. 2 is a golf club head, according to an example embodiment.

FIG. 3 illustrates linear acceleration of a weighted object in a golf club head, according to an example embodiment.

FIG. 4 illustrates an impact event where a golf ball is hit off center, according to an example embodiment.

FIG. 5 illustrates various embodiments of example apparatuses, constructed in accordance with the present disclosure.

DETAILED DESCRIPTION

In general, the present disclosure comprises descriptions of golf club apparatuses and methods of use and, more specifically, but not by limitation, to golf club heads that comprise tubular compartments that house weighted objects. A weighted object traverses linearly within a tubular compartment and functions to impart additional force to a golf ball when the golf ball is struck by the golf club head. This additional force generated by the weighted object is an increase of a force imparted to the golf ball by the golf club head alone. In one embodiment, the weighted object impacts a front end of the tubular compartment when the golf club head meets the golf ball, which is referred to as an impact event. The timing of this impact event is due to the natural bottoming of the arc of the golf club head swing path.

In some embodiments, the golf club head can include a plurality of tubular compartments and/or a plurality of weighted objects that can assist in stabilizing a plane of a clubface of the golf club head during impact events. The weighted objects can reduce rotation of the clubface of the golf club head that occurs when an off-center hit occurs, such as when the golf ball is impacted anywhere but a center of the clubface.

FIG. 1 illustrates an example golf club apparatus 100 that generally comprises a golf club head 102 extending from a shaft 104. The shaft 104 can be positioned at various locations along the golf club head 102.

For clarity of description, the following embodiments will describe a golf club head 102 as a putter head, although the present disclosure can be applied to other golf club heads such as irons, drivers, fairway metals, hybrid clubs, hybrid irons, and other similar golf club heads.

In FIG. 2, an example golf club head 102 comprises a body 106 that includes one or more tubular sidewalls, such as tubular sidewall 108 defining a tubular channel 110. The body 106 can be comprised of one or more materials such as metals or alloys. Examples of materials that may be used for the body 106 include, but are not limited to, aluminum, carbon steel, stainless steel, tungsten, lead, and the like. In some embodiments, the body 106 can be a solid structure (not including the tubular channel 110). In another embodiment the body 106 is a substantially hollow structure that incorporates the tubular sidewall 108 and tubular channel 110.

The golf club head 102 also comprises a front face 112 and, in some embodiments, a rear face 114. The front face 112 may also be referred to as a clubface, which is the portion of the golf club head 102 that impacts a golf ball.

In some embodiments, the tubular sidewall 108 is enclosed on both ends by a sealed front end 116 and a sealed rear end 118, which function to retain a weighted object 120 with the tubular channel 110. The sealed front end 116 and sealed rear end 118 could include plates or caps that cover the respective ends of the tubular channel 110.

In another embodiment, the front face 112 seals the tubular channel 110 rather than the sealed front end 116. Also, the sealed rear end 118 can also seal an opposing end of the tubular channel 110.

According to some embodiments, the tubular sidewall 108, sealed front end 116, and sealed rear end 118 can be manufactured from a material that is different from the material utilized to manufacture the body 106.

In various embodiments, the sealed front end 116 and the sealed rear end 118 are capable of being releaseably coupled to the tubular sidewall 108. For example, the sealed front end 116 can be threaded and received onto a threaded end of the tubular sidewall 108. This configuration allows a user to remove the sealed front end 116 and replace the weighted object 120 to fine tune the performance of the apparatus 100. For example, the user can replace the current weighted object with a heavier weighted object if the user desires additional force or weight for the apparatus 100.

In one embodiment, the tubular channel 110 is substantially cylindrical in shape, although tubular channels of differing shape and size can be utilized in accordance with the present disclosure.

A location of the tubular sidewall 108 and tubular channel 110 within the body 106 can also vary according to design requirements. For example, the tubular sidewall 108 and tubular channel 110 can be located near or on a central axis C of the body 106. In other embodiments, the tubular sidewall 108 and tubular channel 110 are offset from the central axis C by placing the tubular sidewall 108 and tubular channel 110 near either a toe 122 or a heel 124 of the body 106.

In some embodiments, the tubular sidewall 108 is at least partially covered with an insulating material 128. This same (or a different type) insulating material can be added to both the sealed front end 116 and the sealed rear end 118. This insulating material 128 can include any sound damping material or energy absorbing material such as, but not limited to, cork, plastic, or an elastomeric material such as a rubber. The insulating material 128 can also be referred to as a cushion or cushioning material. This insulating material 128 can reduce the noise caused by the weighted object 120 translating within the tubular sidewall 108, if desired.

In various embodiments, the weighted object 120 comprises a shape and size that allows the weighted object 120 to linearly translate within the tubular channel 110. In some embodiments, the weighted object 120 has a diameter that is slightly smaller than the diameter of the tubular sidewall 108 to prevent the weighted object from rattling or bouncing off of the tubular sidewall 108 as it linearly translates in the tubular channel 110.

FIG. 3 illustrates an example of this linear translation. As the golf club head 102 is translated backwards from an initial position P_(I), the weighted object 120 will tend to locate near the front face due to gravity. As the user translates/swings the golf club head 102 back down to its original position P_(I) the weighted object 120 will move away from the front face 112 of the golf club head 102 towards a rear portion of the golf club head 102.

When the golf club head 102 impacts the golf ball 126, the weighted object 120 impacts the sealed front end 116 (or the front face 112) of the tubular channel 110 at approximately the same time. The weight of the weighted object 120 functions to impart kinetic energy to the golf ball 126 in combination with the front face 112 when the body impacts the object. Thus, the kinetic energy imparted by the weighted object 120 and golf club head 102 is greater than the kinetic energy that would be imparted to the golf ball 126 by the golf club head 102 alone.

As such, when the weighted object 120 contacts the sealed front end 116, the weighted object 120 imparts a momentum force onto the sealed front end 116 to cause an increase in kinetic energy transfer to the golf ball 126.

Also, the weighted object 120 imparts its momentum force, which creates a “pop” effect when the golf ball is impacted by the golf club head 102.

The weighted object 120 can be manufactured from any number of materials such as lead or a metallic alloy, just by example. Other materials that may be used include aluminum, carbon steel, stainless steel, tungsten, lead, and the like. In certain embodiments, the weighted object 120 is manufactured from the same material as the body 106. In other embodiments, the weighted object 120 is manufactured from a different material as the body 106. Various combinations of materials may be used for the weighted object 120 and the body 106. In some situations, the weighted object 120 is comprised of a heavier metal than the body 120. The exact materials utilized will depend on preferences of the user, as well as design requirements. For example, the weight of the weighted object 120 can depend on the amount of additional of increased kinetic energy desired, which is also a function of the overall weight of the golf club head 102. The greater the additional kinetic energy force needed, the greater the weight needed for the weighted object 120.

The weighted object 120 can have a variety of shapes and sizes, for example, the weighted object 120 can be spherical, polygonal, or even irregular, depending on linear travel required for the weighted object 120 through the tubular channel 110.

In one embodiment, the weighted object 120 is metallic and the sealed front end 116 (or front face 112) is also a metallic material. The weighted object 120 can ping or click when contacting the sealed front end 116 (or front face 112), which allows the user to appreciate when the weighted object 120 is impacting the sealed front end 116 (or front face 112). The user can then adjust swing speed or swing path to ensure that the ping or click occurs at impact and not before. Thus, the weighted object 120 transforms the golf club head 102 into a training aid that allows the user to judge swing tempo and/or train swing path.

FIG. 4 illustrates an impact event where the golf ball 126 is hit off center. That is, the golf ball 126 is impacted by a portion of the front face 112 that is at a distance away from a linear axis of travel T, or what is also referred to as the swing path. The weighted object 120 assists in reducing and/or eliminating rotation at the toe 122 that would normally occur if the weighted object 120 were not utilized. Toe rotation at impact imparts undesirable spin on the golf ball 126 that pushes it off line relative to the linear axis of travel T. The rotation is represented by a phantom line representation of the body 106.

This front face 112 and body 106 stabilization effect can be enhanced by shifting the tubular sidewall 108, tubular channel 110, and weighted object 120 toward the toe 122 or the heel 124 to counteract different impact misses.

Referring to FIG. 5, additional embodiments of apparatuses are illustrated. These apparatuses are each golf club heads with bodies as described above, in various embodiments.

Apparatus 200 comprises a plurality of tubular sidewalls 202 and 204 defining a plurality of tubular channels 206 and 208, respectively. Each of these comprises a weighted object 210 and 212, for example.

The inclusion of more than one tubular sidewall and weighted object allows for weight balancing proximate a toe 214 and heel 216 of the apparatus 200.

With regard to stabilization, if the weighted objects 210 and 212 are removable, as with the embodiments described above, the user can selectively choose to weigh down the toe or heel. If a user has problems with impacting the golf ball near the toe 214, the user can utilize a weighted object 212 only in the channel formed by sidewall 204, which is proximate the heel 216. The same principle applies to a user who tends to impact the golf ball near the heel 216, rather than in the center of the clubface.

Example apparatus 300 comprises a plurality of sidewalls 302, 304, and 306 defining a plurality of tubular channels 308, 310, and 312. Each of the tubular channels 308, 310, and 312 has a plurality of weighted objects. For example, tubular channel 308 has two weighted objects 314 and 316.

In one embodiment, all of the sidewalls 302, 304, and 306 form tubular channels 308, 310, and 312 that are approximately equal in diameter and length relative to one another, although in another embodiment, such as apparatus 400, this is not required and the tubular channels can vary in diameter and may also vary in length relative to one another.

Apparatus 400 comprises a plurality of sidewalls 402, 404, and 406 that define a plurality of tubular channels 408, 410, and 412. Tubular sidewall 404 defining tubular channel 410 has a smaller diameter than that of sidewalls 402 and 406 defining tubular channels 408 and 412.

A size of the weighted objects can also vary according to design requirements. For example, sidewall 406 and tubular channel 412 comprise weighted objects 414 and 416 that are larger in diameter than weighted objects 418 and 420 that are disposed in tubular channel 410.

Tubular channel 408 comprises more weighted objects than either tubular channel 410 or 412. Again, these are not limiting embodiments, but are merely explanatory of the varied nature of the present disclosure. The performance of the apparatus can be fine-tuned through varying tubular sidewall/channel size, as well as weighted object size and number.

In an exemplary embodiment of apparatus 400, weighted object 418 is comprised of tungsten and weighted objected 420 is comprised of a durable rubber, or a similar type of non-metallic material. When the apparatus 400 impacts the golf ball, the weighted object 418 contacts a sealed front end of the apparatus 400 and the weighted object 420 contacts the weighted object 418. After impact, the weighted objects 418 and 420 will then traverse through the tubular channel 410 in the opposite direction towards a sealed rear end of the apparatus 400. In this example, the use of a weighted object 420 that is comprised of durable rubber reduces the noise made when the weighted object 420 impacts the sealed rear end. Conversely, if the weighted object 420 were comprised of a metallic material such as steel, for example, the noise resulting from the weighted objected 420 impacting the sealed rear end would be significantly louder.

It should be noted that the materials comprising the sidewalls, the tubular channels, and the weighted objects described in the exemplary embodiments above may be comprised of the same material or of different materials. For example, the materials used may comprise various combinations of aluminum, carbon steel, stainless steel, tungsten, lead, and the like.

In one embodiment, tubular channels in any of exemplary apparatuses 100, 200, 300, and 400 are coated or lubricated with oil, Teflon, and the like, to reduce the coefficient of friction. In another embodiment, weighted objects in the tubular channels are coated or lubricated with oil, Teflon, and the like, to reduce the coefficient of friction. In further embodiments, both the tubular channels and the weighted objects are coated or lubricated with oil, Teflon, and the like, to reduce the coefficient of friction.

In some embodiments, tubular channels in any of exemplary apparatuses 100, 200, 300, and 400 are comprised of magnets and weighted objected inside the tubular channels are comprised of anti-magnets. In other embodiments, the tubular channels are comprised of anti-magnets and the weighted objected inside the tubular channels are comprised of magnets.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” or “according to one embodiment” (or other phrases having similar import) at various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Furthermore, depending on the context of discussion herein, a singular term may include its plural forms and a plural term may include its singular form. Similarly, a hyphenated term (e.g., “on-demand”) may be occasionally interchangeably used with its non-hyphenated version (e.g., “on demand”), a capitalized entry (e.g., “Software”) may be interchangeably used with its non-capitalized version (e.g., “software”), a plural term may be indicated with or without an apostrophe (e.g., PE's or PEs), and an italicized term (e.g., “N+1”) may be interchangeably used with its non-italicized version (e.g., “N+1”). Such occasional interchangeable uses shall not be considered inconsistent with each other.

Also, some embodiments may be described in terms of “means for” performing a task or set of tasks. It will be understood that a “means for” may be expressed herein in terms of a structure, device, assembly, sub-assembly, component, and combinations thereof. Alternatively, in some embodiments the “means for” is expressed in terms of prose, or as a flow chart or a diagram.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is noted at the outset that the terms “coupled,” “connected”, “connecting,” “mechanically connected,” etc., are used interchangeably herein to generally refer to the condition of being mechanically or physically connected. It is further noted that various figures (including component diagrams) shown and discussed herein are for illustrative purpose only, and are not drawn to scale.

If any disclosures are incorporated herein by reference and such incorporated disclosures conflict in part and/or in whole with the present disclosure, then to the extent of conflict, and/or broader disclosure, and/or broader definition of terms, the present disclosure controls. If such incorporated disclosures conflict in part and/or in whole with one another, then to the extent of conflict, the later-dated disclosure controls.

The terminology used herein can imply direct or indirect, full or partial, temporary or permanent, immediate or delayed, synchronous or asynchronous, action or inaction. For example, when an element is referred to as being “on,” “connected” or “coupled” to another element, then the element can be directly on, connected or coupled to the other element and/or intervening elements may be present, including indirect and/or direct variants. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.

Although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not necessarily be limited by such terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be necessarily limiting of the disclosure. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “includes” and/or “comprising,” “including” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Example embodiments of the present disclosure are described herein with reference to illustrations of idealized embodiments (and intermediate structures) of the present disclosure. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, the example embodiments of the present disclosure should not be construed as necessarily limited to the particular shapes of regions illustrated herein, but are to include deviations in shapes that result, for example, from manufacturing.

Any and/or all elements, as disclosed herein, can be formed from a same, structurally continuous piece, such as being unitary, and/or be separately manufactured and/or connected, such as being an assembly and/or modules. Any and/or all elements, as disclosed herein, can be manufactured via any manufacturing processes, whether additive manufacturing, subtractive manufacturing and/or other any other types of manufacturing. For example, some manufacturing processes include three dimensional (3D) printing, laser cutting, computer numerical control (CNC) routing, milling, pressing, stamping, vacuum forming, hydroforming, injection molding, lithography and/or others.

Any and/or all elements, as disclosed herein, can include, whether partially and/ or fully, a solid, including a metal, a mineral, a ceramic, an amorphous solid, such as glass, a glass ceramic, an organic solid, such as wood and/or a polymer, such as rubber, a composite material, a semiconductor, a nano-material, a biomaterial and/or any combinations thereof. Any and/or all elements, as disclosed herein, can include, whether partially and/or fully, a coating, including an informational coating, such as ink, an adhesive coating, a melt-adhesive coating, such as vacuum seal and/or heat seal, a release coating, such as tape liner, a low surface energy coating, an optical coating, such as for tint, color, hue, saturation, tone, shade, transparency, translucency, non-transparency, luminescence, anti-reflection and/or holographic, a photo-sensitive coating, an electronic and/or thermal property coating, such as for passivity, insulation, resistance or conduction, a magnetic coating, a water-resistant and/or waterproof coating, a scent coating and/or any combinations thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized and/or overly formal sense unless expressly so defined herein.

Furthermore, relative terms such as “below,” “lower,” “above,” and “upper” may be used herein to describe one element's relationship to another element as illustrated in the accompanying drawings. Such relative terms are intended to encompass different orientations of illustrated technologies in addition to the orientation depicted in the accompanying drawings. For example, if a device in the accompanying drawings is turned over, then the elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. Similarly, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. Therefore, the example terms “below” and “lower” can, therefore, encompass both an orientation of above and below.

While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. The descriptions are not intended to limit the scope of the invention to the particular forms set forth herein. To the contrary, the present descriptions are intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims and otherwise appreciated by one of ordinary skill in the art. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments. 

What is claimed is:
 1. An apparatus, comprising: a body comprising: a tubular sidewall defining a tubular channel; and a front face; and an object disposed inside the tubular channel, the object configured to linearly translate within the tubular channel during movement of the body and impart kinetic energy to an external object in combination with the front face when the body impacts the external object.
 2. The apparatus according to claim 1, wherein the tubular sidewall is at least partially covered with an insulating material.
 3. The apparatus according to claim 1, further comprising a shaft coupled with the body.
 4. The apparatus according to claim 1, wherein the body comprises a rear face.
 5. The apparatus according to claim 1, wherein the tubular sidewall comprises a sealed front end and a sealed rear end.
 6. The apparatus according to claim 5, wherein at least one of the sealed front end and the sealed rear end comprise a cushion material.
 7. The apparatus according to claim 5, wherein at least one of the sealed front end and the sealed rear end are releaseably coupled to the tubular sidewall.
 8. The apparatus according to claim 1, wherein the object is a weighted sphere.
 9. The apparatus according to claim 1, further comprising one or more additional objects disposed within the tubular channel.
 10. The apparatus according to claim 1, wherein, when the object contacts a sealed front end of the tubular sidewall, the object imparts a momentum force onto the sealed front end to cause an increase in kinetic energy transfer to the external object.
 11. The apparatus according to claim 1, wherein the apparatus is a golf club and the body is a putter head.
 12. An apparatus, comprising: a body comprising: a plurality of tubular sidewalls defining a plurality of tubular channels, each having a sealed front end and a sealed rear end; and a front face; and an object disposed inside each of the plurality of tubular channels, the object configured to linearly translate within the tubular channel and contact the sealed front end during an impact event to reduce rotation of the body during the impact event.
 13. The apparatus according to claim 12, wherein the body defines a linear axis of travel and rotation is reduced relative to the linear axis of travel.
 14. An apparatus, comprising: a body comprising: a tubular sidewall defining a tubular channel having a sealed front end and a sealed rear end; and a front face; and a weighted object disposed inside the tubular channel, the weighted object imparting kinetic energy to an external object in combination with the front face when the body impacts the external object.
 15. The apparatus according to claim 14, wherein the kinetic energy imparted by the weighted object and the body in combination is greater than the kinetic energy imparted by the body without the weighted object disposed inside the tubular channel.
 16. The apparatus according to claim 14, further comprising one or more additional weighted objects disposed within the tubular channel.
 17. The apparatus according to claim 16, wherein the apparatus comprises one or more additional tubular sidewalls defining one or more additional tubular channels.
 18. The apparatus according to claim 17, wherein each of the tubular channels and the one or more additional tubular channels comprise a plurality of weighted objects.
 19. The apparatus according to claim 14, wherein the tubular sidewall is at least partially covered with an insulating material.
 20. The apparatus according to claim 14, wherein the weighted object is a metal sphere. 